1. Field of the Invention
The present invention relates to nozzles and jet pumps. More particularly, the present invention relates to nozzles that are used in association with a mixing chamber and a diffuser for the purpose of entraining and mixing solids with a liquid. More particularly, the present invention relates to nozzles having orifices of asymmetrical configuration.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Eductors and jet pumps are designed so as to utilize the Bernoulli principle of when pressure is high, velocity is low and inversely when velocity is high, pressure is low. The term “eductor” or jet pump describes a pump with no moving parts that converts pump pressure into a high-velocity stream (kinetic energy) in order to generate a low pressure. The resulting high-velocity stream produces a low pressure region that draws in and entrains a secondary powder or liquid through the suction inlet (induction port). At the intersection of the issuing motive liquid stream emanating from the nozzle orifice and the secondary additive entering the mixing chamber from the suction inlet, an exchange of momentum produces a mixed stream traveling at a velocity intermediate to the motive fluid and suction velocity. The downstream diffuser section then converts the velocity-pressure back into static pressure at the discharge of the jet pump. In addition to mixing a secondary powder or liquid with a motive liquid, these devices are used to convey, compress and mix gases and vapors.
Many eductor and jet pump designs incorporate tabs, skewed swirls and other downstream attachments in the diffuser section to attempt to generate more intense turbulence, thereby attempting to aid to enhance mixing a primary motive fluid with a secondary additive. These obstructions disturb the streamline flow pattern, causing “eddies” and waves that require considerable energy to support them. This energy is drawn from the primary flow-field (bulk fluid stream), thus reducing the energy level in the flow-field and ultimately reducing the diffuser efficiency. These structure formations may cause the boundary layer to prematurely detach from the pipe wall surface. Relatively larger particles will not follow the bulk liquid flow and will collide and collect on any obstacle in the downstream flow-field.
Generally, eductors and jet pumps are described with three components: (1) a nozzle; (2) an induction port (suction); and (3) a diffuser assembled in a housing. However, two of the most important and functional components of a jet pump are sometimes overlooked. In particular, these are the mixing chamber and the venturi throat section. The mixing chamber is located between the nozzle orifice discharge and the converging inlet into the venturi throat. This is the intersecting, comingling and interacting region between the motive fluid and the secondary additive that has been introduced through the induction port (suction). The first stage of mixing occurs in the mixing chamber and the final stage of mixing occurs in the venturi throat before entering the downstream diffuser section.
The motive nozzle should be designed to produce the highest possible velocity relative to the input energy. The downstream cross-sectional venturi throat should be designed to provide the strongest suction possible before the fluid enters the diffusion section. The diffuser should be designed to provide the greatest amount of energy recovery during conversion.
The diffuser section of the jet pump is a diverging duct that is shaped to gradually recover fluid static pressure from a fluid stream while reducing the downstream flow velocity. It is a means of converting kinetic energy into static pressure. During velocity deceleration and the increase in static pressure, it must be noted that if the diffuser angle of discharge is greater than ten degrees, fluid separation from the conduit wall may occur. In many technical articles, the diffuser discharge angle is recommended to be between seven and twelve degrees. Any higher angle than twelve degrees may cause separation. The diffuser is a pressure recovery tube that is shaped to gradually reduce the velocity and convert the energy into static pressure at the discharge with as little pressure loss as possible.
A key to an efficient and effective diffuser is one that lies in the ability to control the downstream boundary layer and delay detachment. When a flowing fluid stream comes in contact with a stationary surface, a portion of the free-flowing stream velocity is reduced. The free-flowing stream velocity reduction is caused by shear stress between the stationary conduit wall and the moving fluid stream. This frictional flow resistance is known as frictional or viscous drag. A thin layer of fluid adjacent to the conduit or pipe wall surface increases from zero to a mean velocity of the free-flowing stream. The viscous layer near the conduit wall is called the boundary layer. The boundary layer fluid gradually blends into the free-flowing stream.
Diffuser “stall” is the detachment or separation of flow from the diffuser internal surface walls during fluid deceleration causing the formation of “eddies” and a region of unsteady flow within the diffuser. The profile of flow exiting from the diffuser and the diffuser pressure recovery are intimately related to the possibility of diffuser stall. A downstream tendency to wall detachment that leads to diffuser stall can block the diffusion flow causing an unsteady and unstable exit flow that may result in a significant loss of pressure and, if the loss is great enough, a reversal of flow can occur. Boundary layer detachment will cause flow reversal. Wall detachment can be influenced by downstream obstruction, lack of energy input to pressurize the jet pump nozzle, excessive numbers of elbow in the downstream flow line cause frictional drag, and high viscosity fluids that can cause a thick boundary layer.
Diffuser performance is largely governed by the growth of the boundary layer and the degree to which the flow conforms to the diffuser internal surface walls. An efficient diffuser is one which converts the highest possible percentage of kinetic energy into pressure within a given restriction in diffuser length and expansion ratio (i.e. aspect ratio). The intensity of the flow-field velocity is determined by the motive feed pressure (Reynolds number), the total mass content of the admixture, the mixture density and downstream viscous drag.
FIG. 1 is an illustration of prior art eductor assembly. As can be seen, the eductor assembly 10 in FIG. 1 has an inlet nozzle section 12, a mixing chamber 14 and a diffuser section 16. The inlet nozzle section 12 has a tubular portion 18 that extends to a nozzle 20. The tubular portion 18 defines a primary inlet 22. The primary inlet 22 carries a fluid to the nozzle 20. The nozzle 20 has a wide diameter portion 24 opening to the primary inlet 22 and a narrow diameter opening 26 opening to the mixing chamber 14. The narrow diameter opening 26 is adjacent an end of the nozzle 20 opposite the wide diameter opening 24.
In FIG. 1, it can be seen that the mixing chamber 14 is connected to the inlet nozzle section 12 and is in fluid communication with the narrow diameter opening 26 of the nozzle 20. The mixing chamber 14 has an induction port 28 opening thereto and extending therefrom. In particular, it can be seen that the nozzle 20 has an outer surface 30 that extends greatly into the interior of the mixing chamber 14 and generally flows inwardly of the wall 32 of the induction port 28. As such, the outer surface 30 of the nozzle 20 provides a surface whereby any solids or solid particles that are introduced into the induction port 28 can accumulate thereon.
The diffuser section 16 has a secondary inlet 34 with a wide diameter end 36 adjacent the mixing chamber 14 and a narrow diameter end 38 formed inwardly thereof. The secondary inlet 34 is the Venturi of the eductor apparatus. A diffuser 40 is connected by a throat 42 to the secondary inlet 34. The throat 42 is of a generally constant diameter. The diffuser 40 has a narrow diameter end 44 at the throat 42 and a wide diameter end 46 at the end 48 of the diffuser 16.
In the past, various patent have issued relating to such jet pumps and nozzles associated therewith. For example, U.S. Pat. No. 4,505,646, issued on Mar. 19, 1985 to Long et al., describes an eductor pump and process for withdrawing a feed liquid from a container. The eductor pump includes a tubular body having a venturi element mounted inside and near the lower end of the tubular body. A conduit is used for feeding a drive liquid to the venturi element so that the drive liquid can flow through the venturi element and be directed upwardly in the tubular body. A feed liquid access opening in the closed lower end of the tubular body and a passageway from the access opening to the upstream side of the venturi element allows a feed liquid to be inspirated into an upward flow. An outlet is used to remove a mixed stream of feed liquid and drive liquid from the upper part of the tubular body.
U.S. Pat. No. 5,322,222, issued on Jun. 21, 1994 to the present inventor, shows a spiral jet fluid mixer for mixing fluids. This jet mixer has an elongated body having a first inlet nozzle for introduction of a primary fluid, a mixing chamber having a diverging wall and a converging wall, a plurality of angled helical passageways in the diverging wall for introduction of a secondary fluid into the mixing chamber in a spiralling turbulent, initially convergent, flow pattern. Removable inlet nozzles allow a plurality of inlet nozzle orifice diameters.
U.S. Pat. No. 5,522,419, issued on Jun. 4, 1996 to W. S. Sand, teaches an improved venturi eductor for proportionately dispensing of chemicals into flowing water. The venturi eductor has a large anti-siphoning air gap section. The air gap section includes an outer wall and an inner wall with a gap between the walls. Both walls include offset vents or windows that provide an indirect path from the center of the air gap to the exterior of the eductor.
U.S. Pat. No. 5,664,733 issued on Sep. 9, 1997 to the present inventor, shows an improved fluid mixing nozzle in which a first fluid flows therefrom to mix with a second fluid external the nozzle so as to induce vortex creation and chaotic turbulent flow. The nozzle has a body with a cavity extending therethrough from the inlet end to the outlet end. The cross-sectional area of the inlet orifice of the nozzle is greater than its outlet orifice cross-sectional area. The outlet orifice cross-section area shape has a substantially circular central portion and at least one protrusion extending from the perimeter of the central portion. The protrusions are smaller in cross-sectional area than the central portion, are equally spaced about the central portion perimeter, and have a length-to-width ratio from 1 to 2.
U.S. Pat. No. 5,862,829, issued on Jan. 26, 1999 to W. F. Sand, provides a three-piece air gap eductor having an air gap, discharge and venturi sections, a nozzle and a spray shield extending about the venturi section entry so as to constrain turbulence and reduce backsplash and spray exiting the air gap chamber. A water stream engaging the outer-driven venturi is smoothly divided into respective venturi and bypass streams. There is a frustoconical shield capturing turbulent water outside the venturi in a water sheet moving toward a discharge.
U.S. Pat. No. 5,893,519, issued on Apr. 13, 1999 to Cavaretta et al., describes a self-educting, high expansion, multi-agent nozzle. This nozzle includes a body having an eductor section and a barrel section. The eductor section forms a vacuum chamber and first and second chemical ports adapted for connecting to a first and second chemical source. The barrel section forms a pathway between an inlet from the eductor section to an open discharge end. A head forms a tapered conduit between an open motive fluid end adapted for connecting to a motive fluid source and an open exit end. The head is connected to an open head end of the eductor section is in a manner such that the exit end is disposed within the vacuum chamber. A barrel sleeve is movably connected to an exterior surface of the barrel section. The diffuser is mounted within the pathway of the barrel section.
U.S. Pat. No. 5,927,338, issued on Jul. 27, 1999 to Boticki et al., teaches a mixing eductor of a type wherein the primary liquid flows in a downstream direction. A venturi tube is in the eductor and has an annular sharp edge in the main stream so as to divide the stream into a primary stream and a secondary stream around the primary stream. The eductor has an air gap and a flow guide downstream thereof. The flow guide is annular surface around the venturi tube.
U.S. Pat. No. 7,487,795, issued on Feb. 10, 2009 to W. F. Sand, describes an improved chemical dispenser having a plurality of eductors for drawing a chemical into a diluent to produce an effluent. Each eductor selectively discharges via a baffle tube into a single common discharge tube. The effluent flow parameters are insufficient to cause effluent from a selected eductor to flow into a chemical source coupled to a non-selected eductor.
U.S. Pat. No. 7,784,999, issued on Aug. 31, 2010 to the present inventor, shows an eductor apparatus that has an inlet nozzle section with a primary inlet and a nozzle, a mixing chamber connected to the inlet nozzle section and in fluid communication with a narrow diameter opening of the nozzle, and a diffuser section connected to the mixing chamber opposite the inlet nozzle section. The diffuser section has throat formed therein. The throat has a plurality of lobes formed thereon. The plurality of lobes extend longitudinally along the throat. The lobes are generally equally circumferentially spaced from each other around the throat. The narrow diameter opening of the nozzle has another plurality of lobes formed therearound and extending in longitudinally alignment with the plurality of lobes of the throat.
U.S. Pat. No. 8,020,726, issued on Sep. 20, 2011 to Gorenz et al., provides a powder dispersion system which includes an air eductor and a powder-dispensing syringe. The air eductor and a powder-dispensing syringe are inserted into a suction connection of the air eductor.
It is an object of the present invention to provide a mixing nozzle that can be used in a versatile manner for the mixing of liquids or the mixing of the liquids with solids or solid particles.
It is another object of the present invention to provide a mixing nozzle that can be utilized as a stand-alone mixer in a closed conduit or in an open tank.
It is another object of the present invention to provide a mixing nozzle that generates downstream axial switching of the liquid.
It is still a further object of the present invention to provide a jet pump that energizes the downstream boundary layer to prevent “stall”.
It is still a further object of the present invention to provide a jet pump assembly that has an efficient pressure recovery.
It is another object of the present invention to provide a jet pump assembly that can generate a near-perfect vacuum.
It is another object of the present invention to provide a jet pump assembly that can be utilized as a submerged jet pump.
It is another object of the present invention to provide a jet pump assembly that can generate overlapping vortices.
It is still another object of the present invention to provide a jet pump assembly that can mix and deliver a dispersed product.
It is another object of the present invention to provide a jet pump assembly that can deliver longer distances than conventional jet pumps.
It is a further object of the present invention to provide a jet pump assembly that can produce a uniform mixture.
It is a further object of the present invention to provide a jet pump assembly which avoids the production of “fish eyes” in the produced product.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.